Two windows for accumulation; gusts near & over 50 mph

This morning's model data has not done much to increase our overall forecast confidence for a storm coming up the coast and expected to affect the area tonight into Friday, though we feel a little more comfortable saying that major accumulations (6" or more) should stay east/northeast of the immediate metro area. And we continue to be very confident that we'll be seeing intense winds (gusts near and over 50 mph) between tomorrow afternoon and midday Friday.

CWG team snowfall forecast for tonight through early Friday. Confidence: Low.

Since the arrival of precipitation (could start as rain or a rain/snow mix late this afternoon or evening, before changing to all snow overnight) may be less than 12 hours away, we're providing here our best-guess-as-of-now accumulation map.

Reasons for the high uncertainty with this forecast include...

*Storm track and timing: Looking at the latest model data, the D.C. area remains near a border between not much snow to the west, and significant accumulations to the east/northeast. Also, the potential for accumulating snow may come in two windows -- one tonight into early tomorrow, then possibly a lull during the day tomorrow, then more accumulation possible tomorrow night into early Friday. Breaking it up into two pieces may lower overall totals than if it all came at once.

*Temperatures: By overnight tonight, the atmosphere should be cold enough for all snow, but surface temperatures may not be cold enough for all of it to stick, especially if precipitation is too light to bring down colder air from higher up in the atmosphere.

*Traffic jam: A blocking pattern in the atmosphere to our north looks like it will cause the storm's low-pressure center to drift inland and stall as it nears the New York City area tomorrow and tomorrow night. That puts the D.C. area on the precarious edge of snow bands wrapping around to the west and south of the low (these are the bands that would be responsible for the second window of accumulation tomorrow night into early Friday).

Here are our latest accumulation probabilities for tonight through early Friday. These are intended to communicate the range of possible scenarios, as a complement to the more deterministic "best-guess" map above...

Since starting to follow your site during the first Feb storm, I have always liked your analysis of the upcoming weather trends. I work near to BWI, and you all give me better information as a sidenote than I get from the local Baltimore outlets. It looks like up here we are going to get hit again, but do you think we will get that same 2 band type snowfall, or will it be continuous throughout tomorrow?

I am emotionally stuck between disappointment and relief. As a native Washingtonian SnowLover, I have come to the conclusion that it isn't the snow accumulation that's the problem, it's the local reaction (media hype, public and private snow removal, etc.) to the snow accumulation that's the problem. Oh well...hopefully they won't close schools tomorrow as this storm appears to be on track to delivering snow that we ALL (after the kind of winterwe've had...snowLover or not) can laugh at and continue on with life as ususal.

People in DC should not take this storm lightly just because we are not getting over a foot of snow. Even just six inches with strong winds will cause havoc and that is still not out of the question because this storm will be loaded with moisture and it all depends where the snow squalls set up.

Have you guys seen the latest radar. This storm is loaded with moisture and appears to be phasing with the northern jet stream already. The precip is streaming out of the gulf and has now filled in nicely in central and southern VA all the way down to the carolinas and Georgia. If this storm just takes the slightest track closer to the coast and strengthens earlier then we will get the more moderate snowfall.

good, reasoned forecast, and proving once again that delivering weather information in a reasonable tone will bring readers, no need to hype the weather with exclamation points and cheesy adjectives like the site Bastardi and co. work at

TGT11, Please explain how Bastardi has hyped this storm. He has emphatically said that this is not DC's storm. Several days ago, he said that 6" would go through Baltimore. Which by the way is consistent with CWG has said. I am tired of people bashing him who clearly have not heard first hand what he has or has not said. If you do pay to read what he says then I suggest that you don't, because clearly you don't like him. stick to facts!

Just to clarify, while the statement "mountain snow 6+ inches" appears pretty close to Winchester, you guys are talking about the typical upslope on west-facing ridges and the Shenandoah Valley is actually in the 1 inch area, yes?

I would move the 2 to 4 accumulation range a little more to the south otherwise I think CWG is right (for now). I do think there will be more snow than forecasted but that is based on a feeling not on any science. As far as the hype goes, I do not believe that this event has been over-hyped on this site. We are incredibly close to a major snow event and we are not out of the woods yet. I feel we are at the "just have to wait and see what happens" point. On Monday I posted that we would not know about Thursday until today and in some ways, we still don't know.

dmasher1 & hrc2211 & egindc - NYC and PHL accumulations will be upwards of 8" it looks like. And Manhattan may see a bullseye of over a foot.. avoid travel northward for the next 60 hours or so. It will be dangerous; intense wind!

Re: questions for Phil and NYC snow totals, the NWS forecasts can provide some guidance as can Accuweather snow maps.

If I had plans to go to either city in the next couple of days, I'd try to get out of Dodge City (D.C.) by no later than Thursday a.m., and preferably today. I've been on the Jersey Turnpike in white out conditions and it's no fun.

If I were taking a bus or train (or driving) to Phil/NYC on Thurs, I'd take along some extra non-perishable food and beverages and a small blanket. The predicted winds could really create problems for Amtrak and on the Turnpike.

It really depends on when and where this storm explodes as to how much it impacts travel. As we all remember from the storm of two weeks ago, the explosion can happen very quickly (my recollection is that it turned into a bomb between 7:00-7:30 a.m., at least in NW DC).

Thundershock - you may be okay in Bmore early tomorrow afternoon. It won't be easy though. Just "better" than early evening. And temperatures hovering around 33... it should prevent very fast accumulation in the early afternoon in downtown Bmore.

Don't expect a major precipitation-free period here until mid or late June. After the snowstorms, we should expect to get rain and severe weather events through the rest of March into mid-June or later. It's possible that a persistent El Nino could dry us up and begin a heat wave as early as Memorial Day weekend, but that's an outside shot at best. I believe that El Nino's generally bring hotter drier summers around here. The El Nino might also increase this area's tornado threat this spring.

If you feel this storm was "too built up", then it was only in your own mind. I don't think I saw a single forecast from anyone in the Metro area that had DC getting pummelled with this one. For the past several days, the consensus has been that this is a Philly/NYC storm.

Speaking of Syracuse, I'm driving up there on Friday early afternoon from Silver Spring, MD. CWG... what's your estimate on how awful the drive will be? I'm not so worried about the snow on the roads (they handle that pretty well thru PA and NY) as I am about the high winds / drifting. Thoughts?

Think the bigger problem will be the wind. Last time we had a High Wind Warning on a school day Fairfax County Schools closed 3 hours early because the portable classrooms become unsafe in storm force winds. So for those of you expecting schools to be on a 2hr delay tomorrow and/or Friday, you may be in for a surprise.

Does anyone here read the farmer's almanac? Most years is doesn't have much accuracy at all, but they nailed the December and February storms this year and are apparently calling for an even bigger one in the March 7-10 timeframe. Anyone else heard this?

Little, if any, snow will fall in Boston... while Washington, New York and Philadelphia, Pennsylvania, could see as much as 5 inches of snow with locally higher amounts, CNN meteorologist Sean Morris said.

Record snowfall totals of 30 inches or more will be possible across upstate New York, Vermont, New Hampshire and Maine, Morris said. Very strong winds will combine with the heavy snow to produce dangerous white-out conditions and widespread power outages.

The wind may very well cause some problems for you, both blowing around any snow that's fallen, and in terms of blowing the car around. Winds will probably slacken a bit later in the day, so it may be that the later you leave the better. But certainly do check around for updated forecasts Friday morning.

We have been downgraded to a winter weather advisory for 1-3 inches of snow. This storm is nothing compared to any of the others this year even the two six inch suprise storms we saw. This is a real disappoint that DC wont be affected by this histroic storm. I guess it either all or noting for DC this winter. Shall we move forward to spring and sun. What a great winter though at least we got three major snowstorms.

@Axel2 - I hesitate to ask - but curiousity is overriding my fear. What does the Farmer's Almanac say for March 7-10? What do you mean by "bigger"?

Only heard this secondhand, but farmer's almanac said the March storm would be biggest of all this winter, with 2 ft+ being common in the northeast corridor with locally heavier amounts. Again, probably won't happen, but take it for what it's worth :)

I still think 3-4 is possible for DCA but it will be very hard. There just seems to be such a sharp cut off of the snow. I mean just 100 miles away in south east pa they are supposed to get over a foot.

Hey CWG, you guys do a great job covering the weather. I spent most of my life in Buffalo, so I really admire the weather guys. Currently living about 75 miles north of NYC, and we just got 10 inches of slush last night. The exiting storm had marginal temp support (32-34 degrees for the whole event), but strong dynamical cooling which kept most of the heavy precip as snow. Do you foresee a similar scenario with this storm, or the possibility of more of a mixed bag?

The NWS issued a Winter Storm Watch for the upcoming storm yesterday as a contigency (and to CYA). But they made that clear upfront and CWG is being, I think, astutely conservative in their forecasting.

There are several threshholds some/many of us would like to see: 3.2" to break the monthly snowfall record, 4" to hit 60" for the season.

Remember a couple of years ago when we were achingly close to breaking the all-time DCA record for yearly rainfall? Didn't quite happen, though.

But... even though the first part of this storm may be a snow turkey, I wouldn't slam the book shut just yet on this winter.

NWS is seeing that chances for over 3" around the DC Beltway are low; it should likely stay a winter weather advisory.School tomorrow will probably go in the morning; however, i worry about early-dismissals in the midday timeframe, if snow picks up, and temperatures fall? It is difficult to say. But we're not talking about much total snowfall accumulation. I would plan to go in the morning.

Sounds like there's a high degree of confidence in DC getting less than 5", but am I right when I say that it is still difficult to say whether or not areas inside the Beltway get an inch or less or closer to 4"??

I'm afraid this is a storm that will come down to nowcasting. The setup appears to be a pretty rare and complicated situation and I'm not entirely convinced that the models can handle it. Hence the low-confidence of the forecast. But low-confidence to me means ANYTHING CAN HAPPEN - rather than, nothing will probably happen. =-)

Looking at the latest NAM models, it keeps looking more and more like Virginia is in the big hole for this storm, and Maryland isn't going to get much more until you get really close to Delaware. Keeps trending east for the Philly area too.

Those West Virginia Mountains will prevent anything from entering the Old Dominion. I have never understood why the West Virginia Mountains, west of the Shenandoah Valley are so much better at preventing the eastward movement of precipitation than the mountains in Pennsylvania and North Carolina. It certainly isn't because of elevation, because NC has them beat. But they keep the Shenandoah Valley one of the driest areas on the East Coast of North America.

latest NWS forecast out. 2-4" in northern Prince Georges County (1-3" for DC), which seems to be pretty much what CWG says. But NWS seems to think that the second round of precipitation (when the low bombs near NYC)will generally stay north and east of MD Rte. 32. Sounds like Baltimore could still get 6". But in DC, given that the first round of precip will be light and also that temps will only be marginally cold with warm surface temps, it seems as though a slushy inch or two (maybe 3) on the grass (or on top of old snow) will be about it.

@kmp1, plus the soil is saturated from snowmelt, so yes power outages caused by falling trees could be a problem.

@dotyt, if the Pennsylvania loop takes place, then some places could be in Agnes 1972 territory, albeit with snow. However, if the storm loops, it probably won't cross the Susquehanna. Agnes made it all to the way to Dubois. ; ))

@Walter, even if we don't get enough snow for you to sculpt another shark, there are plenty of other fish in the schneezee.

aaf314 - you are right to question the current warmth of surfaces around DC. Not much is going to stick for a while. And you are essentially correct that 2" may fall, but only 1" may stick. Let's say half may melt, what falls.

CWG -- I'm supposed to fly to Atlanta on Thursday night and return to IAD on Friday night. For childcare reasons, I absolutely cannot get stuck in Atlanta (i.e. must get back on Friday). What do you think? This one seems hard to predict...but wondering if you have any advice about potential delays?

Thanks for the quick answer Camden. When will we really know if the major part of the storm has passed us? Tonight? Tomorrow morning? Just want to know when I should plan on throwing in the towel on 4-6 inches of snow.

Ok people I think we've given this snow thing too much media time...after the first 3 storms who gives a rat's a** what falls now it won't compare to anything we've already had. I'm looking at all sorts of different radars and just like all the local channel/weather folks none give you the same picture so I compared them all watched the flow and came up with my own prediction which is i'm not expecting much of anything here in the metro area i.e the District to Woodbridge...

papaskynz -- everything you say is true. This storm is just too big and unique for the models to handle properly, so no one knows for sure what is going on. In any other year, whenever we are on the cusp of snow, it never arrives, or comes in the form of rain. However, given the crazy year this year, and the magnitude of the storm, plus the current radar, I wouldn't be surprised if we got more than 3 inches. All the storm has to do is jiggle 30 miles west or south and there we are.

Winter will be colder than normal, on average, especially north of the Chesapeake Bay. The coldest periods will occur in early to mid- and late January and mid-February. While precipitation will be below normal, slightly above-normal snowfall will occur in many parts of the region. Watch for snow around Thanksgiving, with other snowy periods in mid-January and mid- and late February.

April and May will be warmer and drier than normal, with water reservoirs running low.

Summer will be cooler and drier than normal, with a drought possible despite heavy rain in early June from a tropical storm. The hottest periods will be in mid-June, mid-July, and early to mid-August.

September and October will continue drier than normal, with near-normal temperatures.
Temperature and Precipitation November 2009 to October 2010
Temperature and Precipitation Graph